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RGB for G7000

Started by VideopacBelgium, June 16, 2009, 12:45:43 AM

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Just dropped a mail to Belden through their website.

Here's the matrix on Belden's din-8 connectors so far, I have made some assumptions, but asked Belden to confirm or correct me if wrong.

Interesting enough both the "MAB 8 SH" point to u-shaped connectors, which I am guessing are 262 degree style horseshoe, which would be the same DIN8 connect as used by the Commodore 64 video/audio out.. but the G7400 I have here does not have this DIN out for video so I can not verify (I will have to do that when it arrives.)

Rene, any chance you can verify that the "MAB 8 SH" used in the G7400 RGB mod here;
Is the exact same connection as the original machines produced in France?


This seems to be a horseshoe version, so not exactly the same. Please be aware that the round version and the horseshoe version may not use the same pin numbering. In my G7400 I've used a horseshoe version. I still think it would be best to order a few different versions (only the connectors, not the plugs) and then check which fits best, and then write down which version to use for future mods. Most important is that the footprint of the connector matches the holes in the PCB of the G7400.


Ah.. well, in that case then there's no choice.. shoehorse it is :)

I will order a handfull of circular plugs and lable "DON'T TOUCH.. ONLY FOR FR G7400 EMERGENCY :)"  .. and hide it somewhere in my supply cupboard :) just to be safe to have them if ever needed.

This hole project is really got me enthusiastic for the Videopac again :) I've actually managed to get a nice deal on two broken units (g7000 + g7400) today, picking up later in the week.. lets hope they are as "broken" as the previous one I got.. and otherwise I'm sure I'll find my way on the forum to search some wisdom posted here.

So.. as far as I can see, the only two fitting connectors to the PCB are actually both horseshoe, with same specs.. see picture below.. but I have asked Belden to confirm that..


Wow.. I have spent A LOT of time on this now.. but as I am learning as I go on this little project this have been a great experience so far :) I watched a few how-to videos on Eagle CAD and have been playing around with it the last days.. as I had hoped for working on this Videopac board and copying a diagram and then making choices where to place parts etc. is really helping me understand more!

I have tried to google most stupid questions I came across along the way :) but I can't help unfortunately there are a few left (and atleast 30 I found the answer for, such as which end of an inverter is input and which is output.. hehe)

Rene, I hope you don't mind a final list of questions to help me understand?

Q1. Capacitors missing from kit list?
Whilst checking what I was doing my eye did catch 2 items within the marked red box that were not on the kit list: C852 (between +5 and GND on IC652) and C854 (top left of the marked red box).
Do I add those parts to my project list and include them in my diagram?

Q2. Dots on the box
Whilst drawing my diagram I used solderpads to be able to mark them on my board (line1, 2 etc).
Do I understand the points correctly:
LINE1 to pin27 IC 670
LINE6 -- Blanking Signal -- To inverter 74LS04N and from there to pin 39 of the 8048 (or pin 8 of IC 670)
LINE7 to pin11 IC 656
LINE3 to pin19 IC 670
LINE4 to pin20 IC 670
LINE2 to pin18 IC 670
LINE5 to pin6 IC 656 (matches confirm in previous post)

Q3. the 74LS04N, just to double check;
LINE6 (combined 74LS08N pin12, 2, 5 and 9) goes to pin 1 of 74LS04N.
Pin2 of 74LS04N then goes to pin39 of the 8048?
(i've called this 6A and 6B in my schematics for now just incase I need to alter)

Q4. And question about this part:

I think I've found the problem: there's an error in the circuit diagram of the G7200! For IC 656 they've used a NAND symbol, but in reality it is an AND gate! So if you connect the input of a free inverter to pin 11 of IC 669 of your G7000, and the output of the inverter to your transistor circuit (4k7 resistor), it should work.

lets see if I get this 100% correct, (here my lack of electronics knowledge shows, sorry)..
Do I..
- Connect pin 11 of IC 669 to pin 3 of 74LS04N
- Connect pin 4 of 74LS04N to the junction between R733 and R772 and the TS681

Q5. Removing resistor R713 and switch
- Just to be 100% sure.. no switch, and no R713, just DIN ?
So, if I add a simple on/off switch to the mains cable (i seriously hate taking the plug out and in and I'm not a big fan of sticking cartridges in a slot whilst a machine is running) it will run RGB directly right? (only manual source on tv remote needed to be set to scart input)

Q6. Missing status CVBS?
I noticed crosschecking my kitlist when done with your kitlist, and ended up with
1x 1N4148DO35-7 (D698)
1x 1k (R749)
1x 2v feed
This I assume is the composit signal that will not be used?

Q7 Diagram puzzle?
This is probably me and not being used to diagrams, but the connections between IC 653 and IC 652 are a bit confusing.. for example why does pin 3 on IC 652 show 2 lines to that large center line. I only see it going into pin 8 of IC 653, so I don't quite understand that branch in the drawing.

Q8. And the last question (I hope)
- Is it wise to disconnect RF unit, or should it remain connected? (and does the RGB board impact the RF signal in any way?) ?

oh and I have the entire schematics drawn out now. I have no idea how to share that and it's a bit large to up and a picture. Can I email you the .sch file Rene ?



Is there someone fabricating this so that i can put it in? Cause my skills with these things isn't good.


Yes, I hope to soon :)

Rene has been awesome giving me some help as I am trying to learn how to build and design a layout (sort of as a study project).. so once it is done and I know it works I will gladly share the design and make a few boards extra since I need to order parts anyhow.


Fantastic, write me up for one  :)


:) sure I'll definately post it here, but not before I built and made so I know for sure I did not mess up :)


well, quick update..

unfortunately due to bad health, and later another project that ate a lot of time..
this had to wait for a while :(

the good news is that I have finally ordered a prototype PCB in china this weekend.
Excited to see if they will work, if not I will fix them and do a second run if needed.

A massive BIG THANK YOU goes to Rene!

What you don't see in this thread is that Rene has given me A LOT of feedback in the background and patiently corrected my mistakes, and actually helped me a lot trying to learn and understand basics of drawing schematics and board design in Eagle.

Many thanks Rene!!!!!


My modest contribution to this topic... RGB board for the Videopac G7000.

Works fantastic!

Carlos Bragatto

Quote from: Unstablewarpfield on March 30, 2017, 08:21:55 PM
My modest contribution to this topic... RGB board for the Videopac G7000.

Works fantastic!

Hey man, I just moved to the UK and finally have easy access to RGB tvs. I got a Radiola Jet 471 the other day (and already got it working and connected to my TV, fantastic picture on SCART), and I just bought a Videopac G7000 today.

Are you selling this board? I'm interested in one.